Not so dirt-cheap: how soils could save the day at climate talks

Did you know that in the space of a year, a smallholder farmer in Kenya could capture the same amount of carbon dioxide that a flight from New York to Nairobi and back generates, using just the soils of his or her farm? In other words, if farmers managed their soil in a specific way, they could offset all those carbon emissions.

What’s more, if the world’s farmers clubbed together and managed their soils better, they could offset the total carbon emissions of the whole agricultural sector – and probably more.

As the world's climate experts gather in Germany this month, agriculture needs to be top of the conversation agenda. It's the world’s second biggest greenhouse gas polluter after the energy sector, which includes transport and power generation. Yet although agriculture, excluding deforestation, is responsible for around 13 percent of all global greenhouse gas emissions, research shows that with the right farming practices, it’s possible to trap up to 15 percent of all human made carbon dioxide in the soil.

But here’s the million-dollar question: What’s in it for farmers? After all, they are the ones that need to do the hard work. Farmers are more concerned about feeding their families and earning an income than sucking up carbon dioxide from jet-setting folk. There aren’t swathes of land just sitting around waiting to store more carbon – land is a source of food, income and livelihoods, and it needs to be farmed.

Farmer Mercy Wambui showing how rainwater run-off has affected her crops further down the hill. CIAT and WLE are working with partners to support farmers along the watershed to better manage their land, preventing soil erosion - which clogs up the waterways for other users further downstream.

Georgina Smith / CIAT

What we know:

Our research shows that how the soil is managed on farms has a massive impact on how much carbon is sequestered in the soil. The soil type, what has been planted on the farm for the last decades, ways of managing the soil like hoeing or how much compost or manure is added, all play a part.

We also know that the methods we’re currently advocating for improving soil fertility, like protecting the surface of the soil with maize stalks after harvest (Conservation Agriculture) or improved seeds and fertilizer management (Integrated Soil Fertility Management), are not enough to keep carbon in the soil.

Paying farmers to manage their land better, or providing some kind of financial incentive for those who have to do the work, will have to be an option if we are serious about meeting our climate targets – like those set out in the Paris Agreement.

Harder policy actions are needed as well, to curb harmful practices which damage the soil and set us back decades in reclaiming degraded land.

For over a decade, CIAT has tested agronomic and soil management practices in Western Kenya. From minimum tillage to integrated soil fertility management, these trials are the most comprehensive picture of tropical soil health that we have in Kenya.

Georgina Smith / CIAT

What we don’t know:

Soils are a massive carbon sink. Yet, even though we know about the potential to sink more carbon in the soil, we don’t know how much carbon we could potentially store. An extra 5 to 15 percent is a conservative estimate: we don’t have the high resolution data we need about all the different types of soil – especially not in Africa – to say for sure what is possible.

We also don’t know exactly what types of farming systems promote carbon sequestration in the soil over time. CIAT’s soil trials – probably the oldest in East Africa – show that management practices we are currently promoting, such as Conservation Agriculture and Integrated Soil Fertility Management, can slow down losing carbon from the soil, but cannot entirely prevent it.

In some ways this is good news: it means the potential to become carbon neutral in agriculture – and even to sink more carbon in the soil – is massive if we become more efficient in managing soils and if more farmers take them up and apply them.

Digging trenches for water harvesting. Debre Berhan, Central Ethiopia

Georgina Smith / CIAT

What we need:

The scientific community does already have large amounts of data about what kinds of soils we have, but we need higher resolution data – especially in Africa – and better information about what hinders farmers from investing in soil conserving practices. Also, funding researchers to develop robust prediction models to determine hotspots of potential carbon sequestration that are applicable worldwide, would be a good start.

When we have this information, the research community will be able to better advise policy and decision makers about where to invest in carbon capture. Then, we can work with farmers to take part in these programs, so they’re still bringing in an income for their families while protecting the soil and storing carbon at the same time.

Forests have got REDD+. Carbon offsetting is a thing. Sequestering more carbon in our soil is going to have to feature somewhere on our global agenda – in hard-hitting targets and realistic goals - if we’re serious about meeting climate targets. And if we need to keep making those trips to New York.

The latest episode of the Thrive podcast takes a close look at the ground beneath our feet. Soil, on which terrestrial life depends, is often ignored precisely because it is everywhere and yet invisible.

In recent years, carbon sequestration has gained tremendous momentum and national and international initiatives have been taken up. But as to exactly how much of this carbon can be mopped up through sequestration is up to debate.

Soil, and what it means for human survival, hasn’t gotten this much attention since the 1970s and 1980s. But as soils return to the high tables of policymaker, who will be the winners? Fertiliser companies or smallholders? Land grabbers or the hungry?

Related publications

CGIAR Research Program on Water, Land and Ecosystems (WLE). 2017. Healthy soils for productive and resilient agricultural landscapes. Colombo, Sri Lanka: International Water Management Institute (IWMI). CGIAR Research Program on Water, Land and Ecosystems (WLE). 12p. (WLE Towards Sustainable Intensification: Insights and Solutions Brief 2). doi:10.5337/2017.211

CGIAR Research Program on Water, Land and Ecosystems (WLE). 2015. Shining a light below the surface: Mapping soil properties in Africa. Colombo, Sri Lanka: CGIAR Research Program on Water, Land and Ecosystems (WLE).

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The views and opinions expressed in this blog are strictly those of the author of each post. They do not represent the opinions of the CGIAR Research Program on Water, Land and Ecosystems (WLE) or of the International Water Management Institute (IWMI) or any associated partners. This is an open space for constructive scientific discussion. If you disagree with the opinions or information displayed, please leave a comment or write to the editor: wle(at)cgiar.org.